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-rw-r--r--fs/autofs/dev-ioctl.c748
1 files changed, 748 insertions, 0 deletions
diff --git a/fs/autofs/dev-ioctl.c b/fs/autofs/dev-ioctl.c
new file mode 100644
index 0000000000000..ea4ca1445ab78
--- /dev/null
+++ b/fs/autofs/dev-ioctl.c
@@ -0,0 +1,748 @@
+/*
+ * Copyright 2008 Red Hat, Inc. All rights reserved.
+ * Copyright 2008 Ian Kent <raven@themaw.net>
+ *
+ * This file is part of the Linux kernel and is made available under
+ * the terms of the GNU General Public License, version 2, or at your
+ * option, any later version, incorporated herein by reference.
+ */
+
+#include <linux/miscdevice.h>
+#include <linux/compat.h>
+#include <linux/syscalls.h>
+#include <linux/magic.h>
+
+#include "autofs_i.h"
+
+/*
+ * This module implements an interface for routing autofs ioctl control
+ * commands via a miscellaneous device file.
+ *
+ * The alternate interface is needed because we need to be able open
+ * an ioctl file descriptor on an autofs mount that may be covered by
+ * another mount. This situation arises when starting automount(8)
+ * or other user space daemon which uses direct mounts or offset
+ * mounts (used for autofs lazy mount/umount of nested mount trees),
+ * which have been left busy at at service shutdown.
+ */
+
+typedef int (*ioctl_fn)(struct file *, struct autofs_sb_info *,
+ struct autofs_dev_ioctl *);
+
+static int check_name(const char *name)
+{
+ if (!strchr(name, '/'))
+ return -EINVAL;
+ return 0;
+}
+
+/*
+ * Check a string doesn't overrun the chunk of
+ * memory we copied from user land.
+ */
+static int invalid_str(char *str, size_t size)
+{
+ if (memchr(str, 0, size))
+ return 0;
+ return -EINVAL;
+}
+
+/*
+ * Check that the user compiled against correct version of autofs
+ * misc device code.
+ *
+ * As well as checking the version compatibility this always copies
+ * the kernel interface version out.
+ */
+static int check_dev_ioctl_version(int cmd, struct autofs_dev_ioctl *param)
+{
+ int err = 0;
+
+ if ((param->ver_major != AUTOFS_DEV_IOCTL_VERSION_MAJOR) ||
+ (param->ver_minor > AUTOFS_DEV_IOCTL_VERSION_MINOR)) {
+ pr_warn("ioctl control interface version mismatch: "
+ "kernel(%u.%u), user(%u.%u), cmd(0x%08x)\n",
+ AUTOFS_DEV_IOCTL_VERSION_MAJOR,
+ AUTOFS_DEV_IOCTL_VERSION_MINOR,
+ param->ver_major, param->ver_minor, cmd);
+ err = -EINVAL;
+ }
+
+ /* Fill in the kernel version. */
+ param->ver_major = AUTOFS_DEV_IOCTL_VERSION_MAJOR;
+ param->ver_minor = AUTOFS_DEV_IOCTL_VERSION_MINOR;
+
+ return err;
+}
+
+/*
+ * Copy parameter control struct, including a possible path allocated
+ * at the end of the struct.
+ */
+static struct autofs_dev_ioctl *
+copy_dev_ioctl(struct autofs_dev_ioctl __user *in)
+{
+ struct autofs_dev_ioctl tmp, *res;
+
+ if (copy_from_user(&tmp, in, AUTOFS_DEV_IOCTL_SIZE))
+ return ERR_PTR(-EFAULT);
+
+ if (tmp.size < AUTOFS_DEV_IOCTL_SIZE)
+ return ERR_PTR(-EINVAL);
+
+ if (tmp.size > AUTOFS_DEV_IOCTL_SIZE + PATH_MAX)
+ return ERR_PTR(-ENAMETOOLONG);
+
+ res = memdup_user(in, tmp.size);
+ if (!IS_ERR(res))
+ res->size = tmp.size;
+
+ return res;
+}
+
+static inline void free_dev_ioctl(struct autofs_dev_ioctl *param)
+{
+ kfree(param);
+}
+
+/*
+ * Check sanity of parameter control fields and if a path is present
+ * check that it is terminated and contains at least one "/".
+ */
+static int validate_dev_ioctl(int cmd, struct autofs_dev_ioctl *param)
+{
+ int err;
+
+ err = check_dev_ioctl_version(cmd, param);
+ if (err) {
+ pr_warn("invalid device control module version "
+ "supplied for cmd(0x%08x)\n", cmd);
+ goto out;
+ }
+
+ if (param->size > AUTOFS_DEV_IOCTL_SIZE) {
+ err = invalid_str(param->path, param->size - AUTOFS_DEV_IOCTL_SIZE);
+ if (err) {
+ pr_warn(
+ "path string terminator missing for cmd(0x%08x)\n",
+ cmd);
+ goto out;
+ }
+
+ err = check_name(param->path);
+ if (err) {
+ pr_warn("invalid path supplied for cmd(0x%08x)\n",
+ cmd);
+ goto out;
+ }
+ }
+
+ err = 0;
+out:
+ return err;
+}
+
+/*
+ * Get the autofs super block info struct from the file opened on
+ * the autofs mount point.
+ */
+static struct autofs_sb_info *autofs_dev_ioctl_sbi(struct file *f)
+{
+ struct autofs_sb_info *sbi = NULL;
+ struct inode *inode;
+
+ if (f) {
+ inode = file_inode(f);
+ sbi = autofs_sbi(inode->i_sb);
+ }
+ return sbi;
+}
+
+/* Return autofs dev ioctl version */
+static int autofs_dev_ioctl_version(struct file *fp,
+ struct autofs_sb_info *sbi,
+ struct autofs_dev_ioctl *param)
+{
+ /* This should have already been set. */
+ param->ver_major = AUTOFS_DEV_IOCTL_VERSION_MAJOR;
+ param->ver_minor = AUTOFS_DEV_IOCTL_VERSION_MINOR;
+ return 0;
+}
+
+/* Return autofs module protocol version */
+static int autofs_dev_ioctl_protover(struct file *fp,
+ struct autofs_sb_info *sbi,
+ struct autofs_dev_ioctl *param)
+{
+ param->protover.version = sbi->version;
+ return 0;
+}
+
+/* Return autofs module protocol sub version */
+static int autofs_dev_ioctl_protosubver(struct file *fp,
+ struct autofs_sb_info *sbi,
+ struct autofs_dev_ioctl *param)
+{
+ param->protosubver.sub_version = sbi->sub_version;
+ return 0;
+}
+
+/* Find the topmost mount satisfying test() */
+static int find_autofs_mount(const char *pathname,
+ struct path *res,
+ int test(const struct path *path, void *data),
+ void *data)
+{
+ struct path path;
+ int err;
+
+ err = kern_path_mountpoint(AT_FDCWD, pathname, &path, 0);
+ if (err)
+ return err;
+ err = -ENOENT;
+ while (path.dentry == path.mnt->mnt_root) {
+ if (path.dentry->d_sb->s_magic == AUTOFS_SUPER_MAGIC) {
+ if (test(&path, data)) {
+ path_get(&path);
+ *res = path;
+ err = 0;
+ break;
+ }
+ }
+ if (!follow_up(&path))
+ break;
+ }
+ path_put(&path);
+ return err;
+}
+
+static int test_by_dev(const struct path *path, void *p)
+{
+ return path->dentry->d_sb->s_dev == *(dev_t *)p;
+}
+
+static int test_by_type(const struct path *path, void *p)
+{
+ struct autofs_info *ino = autofs_dentry_ino(path->dentry);
+
+ return ino && ino->sbi->type & *(unsigned *)p;
+}
+
+/*
+ * Open a file descriptor on the autofs mount point corresponding
+ * to the given path and device number (aka. new_encode_dev(sb->s_dev)).
+ */
+static int autofs_dev_ioctl_open_mountpoint(const char *name, dev_t devid)
+{
+ int err, fd;
+
+ fd = get_unused_fd_flags(O_CLOEXEC);
+ if (likely(fd >= 0)) {
+ struct file *filp;
+ struct path path;
+
+ err = find_autofs_mount(name, &path, test_by_dev, &devid);
+ if (err)
+ goto out;
+
+ filp = dentry_open(&path, O_RDONLY, current_cred());
+ path_put(&path);
+ if (IS_ERR(filp)) {
+ err = PTR_ERR(filp);
+ goto out;
+ }
+
+ fd_install(fd, filp);
+ }
+
+ return fd;
+
+out:
+ put_unused_fd(fd);
+ return err;
+}
+
+/* Open a file descriptor on an autofs mount point */
+static int autofs_dev_ioctl_openmount(struct file *fp,
+ struct autofs_sb_info *sbi,
+ struct autofs_dev_ioctl *param)
+{
+ const char *path;
+ dev_t devid;
+ int err, fd;
+
+ /* param->path has already been checked */
+ if (!param->openmount.devid)
+ return -EINVAL;
+
+ param->ioctlfd = -1;
+
+ path = param->path;
+ devid = new_decode_dev(param->openmount.devid);
+
+ err = 0;
+ fd = autofs_dev_ioctl_open_mountpoint(path, devid);
+ if (unlikely(fd < 0)) {
+ err = fd;
+ goto out;
+ }
+
+ param->ioctlfd = fd;
+out:
+ return err;
+}
+
+/* Close file descriptor allocated above (user can also use close(2)). */
+static int autofs_dev_ioctl_closemount(struct file *fp,
+ struct autofs_sb_info *sbi,
+ struct autofs_dev_ioctl *param)
+{
+ return ksys_close(param->ioctlfd);
+}
+
+/*
+ * Send "ready" status for an existing wait (either a mount or an expire
+ * request).
+ */
+static int autofs_dev_ioctl_ready(struct file *fp,
+ struct autofs_sb_info *sbi,
+ struct autofs_dev_ioctl *param)
+{
+ autofs_wqt_t token;
+
+ token = (autofs_wqt_t) param->ready.token;
+ return autofs_wait_release(sbi, token, 0);
+}
+
+/*
+ * Send "fail" status for an existing wait (either a mount or an expire
+ * request).
+ */
+static int autofs_dev_ioctl_fail(struct file *fp,
+ struct autofs_sb_info *sbi,
+ struct autofs_dev_ioctl *param)
+{
+ autofs_wqt_t token;
+ int status;
+
+ token = (autofs_wqt_t) param->fail.token;
+ status = param->fail.status < 0 ? param->fail.status : -ENOENT;
+ return autofs_wait_release(sbi, token, status);
+}
+
+/*
+ * Set the pipe fd for kernel communication to the daemon.
+ *
+ * Normally this is set at mount using an option but if we
+ * are reconnecting to a busy mount then we need to use this
+ * to tell the autofs mount about the new kernel pipe fd. In
+ * order to protect mounts against incorrectly setting the
+ * pipefd we also require that the autofs mount be catatonic.
+ *
+ * This also sets the process group id used to identify the
+ * controlling process (eg. the owning automount(8) daemon).
+ */
+static int autofs_dev_ioctl_setpipefd(struct file *fp,
+ struct autofs_sb_info *sbi,
+ struct autofs_dev_ioctl *param)
+{
+ int pipefd;
+ int err = 0;
+ struct pid *new_pid = NULL;
+
+ if (param->setpipefd.pipefd == -1)
+ return -EINVAL;
+
+ pipefd = param->setpipefd.pipefd;
+
+ mutex_lock(&sbi->wq_mutex);
+ if (!sbi->catatonic) {
+ mutex_unlock(&sbi->wq_mutex);
+ return -EBUSY;
+ } else {
+ struct file *pipe;
+
+ new_pid = get_task_pid(current, PIDTYPE_PGID);
+
+ if (ns_of_pid(new_pid) != ns_of_pid(sbi->oz_pgrp)) {
+ pr_warn("not allowed to change PID namespace\n");
+ err = -EINVAL;
+ goto out;
+ }
+
+ pipe = fget(pipefd);
+ if (!pipe) {
+ err = -EBADF;
+ goto out;
+ }
+ if (autofs_prepare_pipe(pipe) < 0) {
+ err = -EPIPE;
+ fput(pipe);
+ goto out;
+ }
+ swap(sbi->oz_pgrp, new_pid);
+ sbi->pipefd = pipefd;
+ sbi->pipe = pipe;
+ sbi->catatonic = 0;
+ }
+out:
+ put_pid(new_pid);
+ mutex_unlock(&sbi->wq_mutex);
+ return err;
+}
+
+/*
+ * Make the autofs mount point catatonic, no longer responsive to
+ * mount requests. Also closes the kernel pipe file descriptor.
+ */
+static int autofs_dev_ioctl_catatonic(struct file *fp,
+ struct autofs_sb_info *sbi,
+ struct autofs_dev_ioctl *param)
+{
+ autofs_catatonic_mode(sbi);
+ return 0;
+}
+
+/* Set the autofs mount timeout */
+static int autofs_dev_ioctl_timeout(struct file *fp,
+ struct autofs_sb_info *sbi,
+ struct autofs_dev_ioctl *param)
+{
+ unsigned long timeout;
+
+ timeout = param->timeout.timeout;
+ param->timeout.timeout = sbi->exp_timeout / HZ;
+ sbi->exp_timeout = timeout * HZ;
+ return 0;
+}
+
+/*
+ * Return the uid and gid of the last request for the mount
+ *
+ * When reconstructing an autofs mount tree with active mounts
+ * we need to re-connect to mounts that may have used the original
+ * process uid and gid (or string variations of them) for mount
+ * lookups within the map entry.
+ */
+static int autofs_dev_ioctl_requester(struct file *fp,
+ struct autofs_sb_info *sbi,
+ struct autofs_dev_ioctl *param)
+{
+ struct autofs_info *ino;
+ struct path path;
+ dev_t devid;
+ int err = -ENOENT;
+
+ if (param->size <= AUTOFS_DEV_IOCTL_SIZE) {
+ err = -EINVAL;
+ goto out;
+ }
+
+ devid = sbi->sb->s_dev;
+
+ param->requester.uid = param->requester.gid = -1;
+
+ err = find_autofs_mount(param->path, &path, test_by_dev, &devid);
+ if (err)
+ goto out;
+
+ ino = autofs_dentry_ino(path.dentry);
+ if (ino) {
+ err = 0;
+ autofs_expire_wait(&path, 0);
+ spin_lock(&sbi->fs_lock);
+ param->requester.uid =
+ from_kuid_munged(current_user_ns(), ino->uid);
+ param->requester.gid =
+ from_kgid_munged(current_user_ns(), ino->gid);
+ spin_unlock(&sbi->fs_lock);
+ }
+ path_put(&path);
+out:
+ return err;
+}
+
+/*
+ * Call repeatedly until it returns -EAGAIN, meaning there's nothing
+ * more that can be done.
+ */
+static int autofs_dev_ioctl_expire(struct file *fp,
+ struct autofs_sb_info *sbi,
+ struct autofs_dev_ioctl *param)
+{
+ struct vfsmount *mnt;
+ int how;
+
+ how = param->expire.how;
+ mnt = fp->f_path.mnt;
+
+ return autofs_do_expire_multi(sbi->sb, mnt, sbi, how);
+}
+
+/* Check if autofs mount point is in use */
+static int autofs_dev_ioctl_askumount(struct file *fp,
+ struct autofs_sb_info *sbi,
+ struct autofs_dev_ioctl *param)
+{
+ param->askumount.may_umount = 0;
+ if (may_umount(fp->f_path.mnt))
+ param->askumount.may_umount = 1;
+ return 0;
+}
+
+/*
+ * Check if the given path is a mountpoint.
+ *
+ * If we are supplied with the file descriptor of an autofs
+ * mount we're looking for a specific mount. In this case
+ * the path is considered a mountpoint if it is itself a
+ * mountpoint or contains a mount, such as a multi-mount
+ * without a root mount. In this case we return 1 if the
+ * path is a mount point and the super magic of the covering
+ * mount if there is one or 0 if it isn't a mountpoint.
+ *
+ * If we aren't supplied with a file descriptor then we
+ * lookup the path and check if it is the root of a mount.
+ * If a type is given we are looking for a particular autofs
+ * mount and if we don't find a match we return fail. If the
+ * located path is the root of a mount we return 1 along with
+ * the super magic of the mount or 0 otherwise.
+ *
+ * In both cases the the device number (as returned by
+ * new_encode_dev()) is also returned.
+ */
+static int autofs_dev_ioctl_ismountpoint(struct file *fp,
+ struct autofs_sb_info *sbi,
+ struct autofs_dev_ioctl *param)
+{
+ struct path path;
+ const char *name;
+ unsigned int type;
+ unsigned int devid, magic;
+ int err = -ENOENT;
+
+ if (param->size <= AUTOFS_DEV_IOCTL_SIZE) {
+ err = -EINVAL;
+ goto out;
+ }
+
+ name = param->path;
+ type = param->ismountpoint.in.type;
+
+ param->ismountpoint.out.devid = devid = 0;
+ param->ismountpoint.out.magic = magic = 0;
+
+ if (!fp || param->ioctlfd == -1) {
+ if (autofs_type_any(type))
+ err = kern_path_mountpoint(AT_FDCWD,
+ name, &path, LOOKUP_FOLLOW);
+ else
+ err = find_autofs_mount(name, &path,
+ test_by_type, &type);
+ if (err)
+ goto out;
+ devid = new_encode_dev(path.dentry->d_sb->s_dev);
+ err = 0;
+ if (path.mnt->mnt_root == path.dentry) {
+ err = 1;
+ magic = path.dentry->d_sb->s_magic;
+ }
+ } else {
+ dev_t dev = sbi->sb->s_dev;
+
+ err = find_autofs_mount(name, &path, test_by_dev, &dev);
+ if (err)
+ goto out;
+
+ devid = new_encode_dev(dev);
+
+ err = path_has_submounts(&path);
+
+ if (follow_down_one(&path))
+ magic = path.dentry->d_sb->s_magic;
+ }
+
+ param->ismountpoint.out.devid = devid;
+ param->ismountpoint.out.magic = magic;
+ path_put(&path);
+out:
+ return err;
+}
+
+/*
+ * Our range of ioctl numbers isn't 0 based so we need to shift
+ * the array index by _IOC_NR(AUTOFS_CTL_IOC_FIRST) for the table
+ * lookup.
+ */
+#define cmd_idx(cmd) (cmd - _IOC_NR(AUTOFS_DEV_IOCTL_IOC_FIRST))
+
+static ioctl_fn lookup_dev_ioctl(unsigned int cmd)
+{
+ static ioctl_fn _ioctls[] = {
+ autofs_dev_ioctl_version,
+ autofs_dev_ioctl_protover,
+ autofs_dev_ioctl_protosubver,
+ autofs_dev_ioctl_openmount,
+ autofs_dev_ioctl_closemount,
+ autofs_dev_ioctl_ready,
+ autofs_dev_ioctl_fail,
+ autofs_dev_ioctl_setpipefd,
+ autofs_dev_ioctl_catatonic,
+ autofs_dev_ioctl_timeout,
+ autofs_dev_ioctl_requester,
+ autofs_dev_ioctl_expire,
+ autofs_dev_ioctl_askumount,
+ autofs_dev_ioctl_ismountpoint,
+ };
+ unsigned int idx = cmd_idx(cmd);
+
+ return (idx >= ARRAY_SIZE(_ioctls)) ? NULL : _ioctls[idx];
+}
+
+/* ioctl dispatcher */
+static int _autofs_dev_ioctl(unsigned int command,
+ struct autofs_dev_ioctl __user *user)
+{
+ struct autofs_dev_ioctl *param;
+ struct file *fp;
+ struct autofs_sb_info *sbi;
+ unsigned int cmd_first, cmd;
+ ioctl_fn fn = NULL;
+ int err = 0;
+
+ cmd_first = _IOC_NR(AUTOFS_DEV_IOCTL_IOC_FIRST);
+ cmd = _IOC_NR(command);
+
+ if (_IOC_TYPE(command) != _IOC_TYPE(AUTOFS_DEV_IOCTL_IOC_FIRST) ||
+ cmd - cmd_first > AUTOFS_DEV_IOCTL_IOC_COUNT) {
+ return -ENOTTY;
+ }
+
+ /* Only root can use ioctls other than AUTOFS_DEV_IOCTL_VERSION_CMD
+ * and AUTOFS_DEV_IOCTL_ISMOUNTPOINT_CMD
+ */
+ if (cmd != AUTOFS_DEV_IOCTL_VERSION_CMD &&
+ cmd != AUTOFS_DEV_IOCTL_ISMOUNTPOINT_CMD &&
+ !capable(CAP_SYS_ADMIN))
+ return -EPERM;
+
+ /* Copy the parameters into kernel space. */
+ param = copy_dev_ioctl(user);
+ if (IS_ERR(param))
+ return PTR_ERR(param);
+
+ err = validate_dev_ioctl(command, param);
+ if (err)
+ goto out;
+
+ fn = lookup_dev_ioctl(cmd);
+ if (!fn) {
+ pr_warn("unknown command 0x%08x\n", command);
+ err = -ENOTTY;
+ goto out;
+ }
+
+ fp = NULL;
+ sbi = NULL;
+
+ /*
+ * For obvious reasons the openmount can't have a file
+ * descriptor yet. We don't take a reference to the
+ * file during close to allow for immediate release,
+ * and the same for retrieving ioctl version.
+ */
+ if (cmd != AUTOFS_DEV_IOCTL_VERSION_CMD &&
+ cmd != AUTOFS_DEV_IOCTL_OPENMOUNT_CMD &&
+ cmd != AUTOFS_DEV_IOCTL_CLOSEMOUNT_CMD) {
+ fp = fget(param->ioctlfd);
+ if (!fp) {
+ if (cmd == AUTOFS_DEV_IOCTL_ISMOUNTPOINT_CMD)
+ goto cont;
+ err = -EBADF;
+ goto out;
+ }
+
+ sbi = autofs_dev_ioctl_sbi(fp);
+ if (!sbi || sbi->magic != AUTOFS_SBI_MAGIC) {
+ err = -EINVAL;
+ fput(fp);
+ goto out;
+ }
+
+ /*
+ * Admin needs to be able to set the mount catatonic in
+ * order to be able to perform the re-open.
+ */
+ if (!autofs_oz_mode(sbi) &&
+ cmd != AUTOFS_DEV_IOCTL_CATATONIC_CMD) {
+ err = -EACCES;
+ fput(fp);
+ goto out;
+ }
+ }
+cont:
+ err = fn(fp, sbi, param);
+
+ if (fp)
+ fput(fp);
+ if (err >= 0 && copy_to_user(user, param, AUTOFS_DEV_IOCTL_SIZE))
+ err = -EFAULT;
+out:
+ free_dev_ioctl(param);
+ return err;
+}
+
+static long autofs_dev_ioctl(struct file *file, unsigned int command,
+ unsigned long u)
+{
+ int err;
+
+ err = _autofs_dev_ioctl(command, (struct autofs_dev_ioctl __user *) u);
+ return (long) err;
+}
+
+#ifdef CONFIG_COMPAT
+static long autofs_dev_ioctl_compat(struct file *file, unsigned int command,
+ unsigned long u)
+{
+ return autofs_dev_ioctl(file, command, (unsigned long) compat_ptr(u));
+}
+#else
+#define autofs_dev_ioctl_compat NULL
+#endif
+
+static const struct file_operations _dev_ioctl_fops = {
+ .unlocked_ioctl = autofs_dev_ioctl,
+ .compat_ioctl = autofs_dev_ioctl_compat,
+ .owner = THIS_MODULE,
+ .llseek = noop_llseek,
+};
+
+static struct miscdevice _autofs_dev_ioctl_misc = {
+ .minor = AUTOFS_MINOR,
+ .name = AUTOFS_DEVICE_NAME,
+ .fops = &_dev_ioctl_fops,
+ .mode = 0644,
+};
+
+MODULE_ALIAS_MISCDEV(AUTOFS_MINOR);
+MODULE_ALIAS("devname:autofs");
+
+/* Register/deregister misc character device */
+int __init autofs_dev_ioctl_init(void)
+{
+ int r;
+
+ r = misc_register(&_autofs_dev_ioctl_misc);
+ if (r) {
+ pr_err("misc_register failed for control device\n");
+ return r;
+ }
+
+ return 0;
+}
+
+void autofs_dev_ioctl_exit(void)
+{
+ misc_deregister(&_autofs_dev_ioctl_misc);
+}
generated by cgit v1.2.3 (git 2.39.1) at 2024-04-23 11:47:50 +0000